Display devices arranged with a thin film transistor in pixels which control emitted light of a light emitting device such as an organic electroluminescence device are being developed. When these display devices are looked at from the incidence direction of light in the pixels, there is a bottom emission type which emits light to the side of a substrate formed with a thin film transistor, and a top emission type which emits light to the upper direction of a pixel. Among these, the top emission type is advantageous in that it is easier to raise the aperture ratio of a pixel compared to the bottom emission type.
In the case where a light emitting device which emits white light is used as the structure of a pixel, a color filter corresponding to red (R), green (G) and blue (B) is arranged on the light emitting side and a color display is performed. In the top emission type, a color filter is not formed directly on the light emitting device but overlaps with a substrate arranged with the color filter in order to face the substrate formed with the light emitting device. A color filter includes a color filter layer which allows light from each color region red (R), green (G) and blue (B) to pass through and a light shielding layer which prevents mixed colors is arranged on the boundary of each color filter.
FIG. 10 (A) is an example of this type of display device and an en exploded view of a part enclosed by the dotted line is shown in FIG. 10 (B). In the display device 10, a light emitting device 24 is formed by stacking a pixel electrode 16 via an insulation layer 14 above a bottom substrate 12, an organic electroluminescence layer (referred to herein as “organic EL layer”) 20, and an upper part electrode 22. A bank layer 18 is arranged to cover the periphery edge section of the pixel electrode 14. A light shielding layer 32 is formed corresponding to the boundary region of the pixel electrode 14 on the upper substrate 30 and above this a color filter layer 34 and overcoat layer 36 are arranged.
In the light emitting device 24, light emitting at the organic EL layer 20 spreads in all directions of 4π when expressed as a solid angle. Light which proceeds in a roughly perpendicular direction from the organic EL layer 20 passes through the color filter layer 34 and is emitted from the upper substrate 30 (path a). Light which proceeds in the direction of the light shielding layer 32 from the organic EL layer 20 is absorbed by the light shielding layer 32 and never emitted to the exterior (path b). On the other hand, light which is emitted in a diagonal direction from the organic EL layer 20 becomes leak light towards an adjacent pixel (path c). Light which leaks to an adjacent pixel can pass through a different color filter layer to the color of its own pixel and thereby mixed colors are generated which affects display properties. In order to shield light leaking to an adjacent pixel, when a width W of the light shielding layer 32 is enlarged, an area of an aperture part which can allow light to pass through is compressed which leads to a decrease in the utilization efficiency of light emitted in the light emitting device.
When a light shielding layer arranged so as to enclose the outline of a color filter is made smaller for effects such as diffraction grating to operate and in order to achieve high resolution of a pixel, a problem is produced whereby light which has passed through an adjacent color filter is refracted and colors become mixed. As a result, even in the case where the size of a pixel is compressed, a display device is disclosed in Japanese Laid Open Patent 2012-209201 which is arranged with a wide translucent layer contacting a light shielding layer arranged on the side of the bottom layer of the color filters in order to suppress mixed colors due to refraction of light which has passed through an adjacent color filter.
The display device disclosed in Japanese Laid Open Patent 2012-209201 is formed in order to reduce light from leaking to an adjacent pixel using a structure of directly stacking a light shielding layer and a translucent layer having a wider width than the light shielding layer. However, since a color filter is present on the upper layer part of the light shielding layer and translucent layer, the distance from the light emitting device is large. As a result, if the width of the translucent layer is not significantly increased more than the light shielding layer, a problem is generated whereby light emitted in a diagonal direction can not be sufficiently absorbed. When the width of the translucent layer is increased, light emitted by a pixel in a perpendicular direction becomes absorbed by the translucent layer and thereby utilization efficiency of light is significantly decreased.